Sort The Characteristics Of Temperate And Polar Glaciers.

Sorting the Characteristics of Temperate and Polar Glaciers

Glaciers, majestic rivers of ice, sculpt landscapes and influence global climate. Understanding their diverse characteristics is crucial for comprehending their role in Earth's systems and predicting their response to climate change. A key distinction lies in the temperature of the glacial ice itself, classifying glaciers into two main categories: temperate and polar. This article will delve into the defining characteristics of each, highlighting their differences and exploring the factors that shape their unique features.

Temperature: The Fundamental Difference

The most significant differentiator between temperate and polar glaciers is their ice temperature.

• Temperate glaciers exist at or near the pressure-melting point of ice. This means that the ice within the glacier is at 0°C (32°F) or very close to it, regardless of the air temperature. This near-melting point allows for significant internal meltwater flow within the glacier.

• Polar glaciers, on the other hand, are considerably colder. The ice within a polar glacier remains well below the pressure-melting point, typically far below 0°C. Consequently, there is significantly less internal meltwater.

Physical Characteristics: A Comparative Analysis

Beyond temperature, several physical characteristics distinguish temperate and polar glaciers:

Ice Structure and Density

• Temperate Glaciers: The near-melting point of temperate glaciers leads to a more porous and less dense ice structure. The presence of liquid water within the ice facilitates processes like recrystallization and the formation of englacial conduits (channels within the glacier for water flow).

• Polar Glaciers: The consistently cold temperatures of polar glaciers result in a denser, more compact ice structure with minimal internal meltwater. This ice is typically clearer and less fractured than temperate glacial ice. The low temperature inhibits recrystallization processes, leading to a different ice fabric.

Glacier Dynamics: Flow and Movement

• Temperate Glaciers: The presence of meltwater significantly influences the flow dynamics of temperate glaciers. Water acts as a lubricant, facilitating faster ice movement and contributing to basal sliding (the movement of the glacier over its bed). This can lead to rapid changes in glacier velocity and surges (periods of unusually rapid glacier advancement). Crevasses, deep cracks in the glacier surface, are more common in temperate glaciers due to the interplay of ice flow and meltwater.

• Polar Glaciers: The lack of substantial meltwater results in slower ice flow in polar glaciers. Movement is primarily driven by internal deformation (the gradual flowing and shifting of ice crystals within the glacier). Basal sliding is less significant, and the movement is generally more uniform and predictable. Crevasses are typically less prevalent in polar glaciers, reflecting the more rigid ice.

Surface Features: Morphology and Topography

• Temperate Glaciers: The combination of meltwater and higher flow rates creates distinctive surface features in temperate glaciers. These include extensive supraglacial lakes (lakes on the glacier's surface), moulins (vertical shafts carrying meltwater to the glacier bed), and a more irregular, sculpted surface. The action of meltwater often leads to erosion and deposition of sediment, creating various landforms.

• Polar Glaciers: Polar glaciers often exhibit smoother, more uniform surfaces. Surface features are generally less pronounced, and supraglacial lakes are less common due to limited meltwater. Accumulation of snow and ice dominates the surface processes, leading to a relatively flatter topography.

Glacial Erosion and Deposition: Shaping the Landscape

• Temperate Glaciers: The high meltwater content in temperate glaciers enhances their erosional capacity. Meltwater can flow beneath the glacier, facilitating basal erosion and the formation of U-shaped valleys. The transport and deposition of sediment by meltwater create a range of landforms, including eskers (long, winding ridges of sediment deposited by meltwater streams), kames (mounds of sediment deposited by meltwater), and outwash plains (flat plains composed of sediment deposited by meltwater rivers).

• Polar Glaciers: While polar glaciers also erode and transport sediment, the process is slower and less intense due to limited meltwater. Erosion is predominantly achieved through abrasion (the grinding of rock against the glacier base) and plucking (the removal of rock fragments from the glacier bed). Deposition occurs, but typically on a smaller scale than in temperate glaciers.

Geographical Distribution: Where They Thrive

The temperature and climate of a region heavily influence glacier type.

• Temperate Glaciers: Temperate glaciers are found primarily in higher-latitude regions with warmer climates, such as the coastal areas of Alaska, British Columbia, Norway, and New Zealand. They are often found at lower altitudes compared to polar glaciers.

• Polar Glaciers: Polar glaciers are predominantly found in high-latitude regions characterized by extremely cold temperatures, such as Antarctica, Greenland, and the Arctic islands. They are typically found at high altitudes, even extending down to sea level in polar regions.

The Impact of Climate Change: A Critical Consideration

Climate change significantly impacts both temperate and polar glaciers.

• Temperate Glaciers: Rising global temperatures are accelerating the melting of temperate glaciers. Increased meltwater contributes to faster glacier flow, potentially leading to increased glacial lake outburst floods (GLOFs). The loss of these glaciers has profound effects on water resources, ecosystems, and sea-level rise.

• Polar Glaciers: Although seemingly less affected by temperature increases on their surface, polar glaciers are vulnerable to changes in precipitation patterns and ocean temperatures. Increased melting at their base due to warmer ocean water accelerates their contribution to sea-level rise. Calving (the breaking off of large chunks of ice from the glacier's terminus) is also becoming more frequent, leading to dramatic ice loss.

Investigative Techniques: Understanding Glacial Processes

Scientists employ a variety of techniques to study temperate and polar glaciers. These include:

• Glaciological Surveys: These involve direct measurements of glacier thickness, velocity, and surface features. Techniques such as GPS measurements, radar sounding, and ground-penetrating radar are used to gather this information.

• Remote Sensing: Satellite imagery and aerial photography are crucial for monitoring glacier extent, changes in ice cover, and the detection of surface features.

• Isotope Analysis: Analyzing the isotopic composition of ice cores provides valuable insights into past climate conditions and glacier behavior.

• Meltwater Monitoring: Measurements of meltwater discharge from glaciers help in assessing the contribution of glaciers to river flow and sea-level rise.

Conclusion: A Holistic Understanding

The distinction between temperate and polar glaciers highlights the diverse nature of these dynamic ice bodies. While temperature is the fundamental differentiating factor, this leads to a cascade of other differences in their physical characteristics, dynamics, and impact on the environment. Understanding these differences is vital for accurately predicting their response to climate change and mitigating its consequences. Continued research using advanced techniques is crucial for improving our knowledge and ensuring effective glacial management in a changing world. The future of these impressive natural wonders hinges on our ability to understand their intricacies and the forces that shape their existence. The ongoing study of temperate and polar glaciers provides invaluable insights into Earth's climate history, its present state, and the implications for the future.